One of the traditional commodity promotion methods is to show promotion video on a display (electronic POP terminal, etc.) installed on a showcase and including a memory card or DVD to advertise commodities to customers. In this method, however, promotion information is only shown to customers unilaterally and does not change. Accordingly, customers do not necessarily give attention to such information. In recent years, there have been considered methods of, in response to the behavior of a customer, providing information to the customer using IT technology to attract the attention of the customer. One of specific methods being considered involves detecting that a customer has picked up a commodity and displaying information related to the commodity on an electronic POP terminal.
Known examples of the method of detecting that a customer has picked up a commodity include a method of attaching RF tags disclosed in Patent Literature 1 to commodities and using a phenomenon in which when a customer picks up a commodity, tag information is read. However, this RFID system usage method has the following problems.
A first problem is that the tag information of an RF tag may be read illegally. For example, if RF tags are used to manage commodities on a showcase at a retail store, a third party other than a consumer (customer) who is about to purchase one commodity or a store clerk who is involved in commodity management can read the tag information of an RF tag attached to the commodity. The third party can, for example, associate the commodity which the customer is about to purchase or has purchased, with the customer, resulting in a privacy violation problem.
A second problem is that an RF tag is costly. While the per-unit cost of UHF-band tags is currently being reduced to levels less than 10 yen, this cost is higher by about double digits than, for example, barcodes, which are also being used to manage articles, particularly, commodities. For this reason, it is difficult to attach an RF tag to an article whose cost is approximately 1000 yen or less, in terms of cost.
Patent Literature 1 discloses a technology for coping with these problems. As with the above RFID system usage method, the technology of Patent Literature 1 aims to manage articles. More specifically, Patent Literature 1 relates to a smart shelf using an RFID system, more specifically, to a technology for monitoring the presence or absence of articles on a shelf.
In Patent Literature 1, multiple RF tags are disposed on a shelf, and managed (hereinafter referred to as “target articles”) are placed in such a manner that the target articles hinder an RFID reader from reading the RF tags disposed on the shelf. Specifically, in Patent Literature 1, the target articles are placed between the RF tags and an antenna included in the RFID reader. In Patent Literature 1, the number of articles is monitored according to the following procedure.    (a) The RFID reader emits electromagnetic waves toward the shelf.    (b) The RFID reader measures the number of RF tags whose tag information it cannot read due to the presence of articles corresponding to the RF tags.    (c) The RFID reader determines the number of articles on the basis of the information obtained in (b).
Note that when the articles are placed between the reader and tags, the RF tags are adjusted so that the articles hinder the reader from reading the tags.
According to the technology of Patent Literature 1, when one target article is placed between the RFID reader and a corresponding RF tag, that is, the target article is present on the shelf, the article blocks the line of sight between the RF tag and RFID reader. Thus, the RFID reader is hindered from reading the tag information of the RF tag. That is, when target articles are present, the RFID reader cannot read the tag information of RF tags corresponding to the articles and thus can detect that target articles are present. On the other hand, when one target article is absent on the shelf, that is, the target article is not placed between the RFID reader and a corresponding RF tag, there is no target article which blocks the line-of-sight between the RF tag and RFID reader. Accordingly, the RFID reader can read the tag information of the RF tag and thus can detect that the article is absent. As seen above, Patent Literature 1 can detect the presence or absence of the articles and thus can manage the articles on the shelf. Note that articles that can be managed must contain a metal, water, or the like, which hinders transmission of energy with a radio frequency.
According to the technology of Patent Literature 1, the RF tags are not attached to the target articles but left on the shelf. Thus, a third party is prevented from illegally reading the tag information of an RF tag attached to any target article, thereby preventing privacy violation or information security problem. This is, the technology of Patent Literature 1 does not cause illegal reading of the tag information of a RF tag by a third party, which is the first problem. Further, the technology of Patent Literature 1 allows the RF tags to be used repeatedly, since the RF tags are not attached but left on the shelf. Thus, the per-article tag cost substantially becomes a value obtained by dividing the tag cost by the number of times the tag is used. That is, according to the technology of Patent Literature 1, the problem that an RF tag is costly, which is the second problem, is solved by using the tag a sufficient number of times.